Silicon carbide resistor mounting



March 31, 1959 R. L. HUFFMAN SILICON CARBIDE RESISTOR MOUNTING Filed May10, 1957 Sect AA INVENTOR Hoben L. Huf man United States Patent SILICONCARBIDE RESISTOR MOUNTING Robert L. Hulfman, Palatine, 111., assignor toGeneral Telephone Laboratories, Incorporated, Chicago, 11]., acorporation of Delaware Application May 10, 1957, Serial No. 658,365

1 Claim. (Cl. 201-63) This invention relates to silicon carbon resistorsand more particularly to the encapsulation of these resistors.

An object of the invention is to provide terminals and a casing for adisc shaped resistor which components can readily be assembled into acompleted unit.

A further object of the invention is a pair of terminals cooperativelyformed to contact and hold the resistance unit firmly in place whilealso performing the necessary function of providing interconnectingmeans.

A feature of the invention is to provide a capsule into which the partscan be placed, and further by the use of a single retaining ring inconjunction with the capsule the entire resistor assembly is held as asolid, compact unit.

The advantages of the present invention will be readily seen whenreviewed with the drawings. Fig. 1 shows a front view of an assembledresistor and Fig. 2 the side view. Fig. 3 shows a front view of aterminal and Fig. 4 a side view. Fig. 5 shows the capsule in a frontview and Fig. 6 a side view. Fig. 7 shows a cross section of a portionof Fig. 5 which in effect is an enlarged view of a portion of Fig. 6.

Figs. 5, 6 and 7 show the casing or capsule 12. The capsule is formedfrom a portion of phenolic tubing having an inner diameter g. The tubinghas its center bored out to diameter 71 and has a ring 21 scored on theinner circumference at diameter 11. Two slots 22 and 23 are formed inthe tubing walls as shown in Fig. 6.

Figs. 3 and 4 shows a terminal 13 which is made of a conductive materialsuch as brass. The terminal has a circular surface area 24 roughlyequivalent to that of the silicon carbide disc 15 of Fig. 2 and theterminal has a protruding terminal leg 25. Three nodes 16, 17 and 18 arebulged in the surface area 24 of the terminal. These nodes areequi-angularly spaced on a common circumference. These nodes insure thata firm contact will be made between the disc and the terminal surface.The surface area 24 is then dished as shown in Fig. 4 to form a springaction in the terminal surface area and thus 2,880,295 Patented Mar. 31,1959 ice 2 insure that sufficient contact pressure is achieved betweenthe terminal and the disc.

The resistor is assembled as follows:

Terminal leg 25 is placed through slot 23 in such a manner that theconcave side of surface 24 is placed against inner wall 26 (shown inFig. 7). The convex surface 24 with its nodes 16, 17 and 18 is therebyexposed. Silicon carbide disc 15 is then inserted against the nodes andthe convexity. A second terminal 14 which is identical to terminal 13 isplaced with its convex surface adja cent the disc 15. The nodes ofterminal 14 thereby contact disc 15. A circular retaining ring 11 havingan open portion as shown in Fig. 1 and having spring properties is thencompressed and slipped into the slot 21 shown in Fig. 7.

When fully assembled, the spring pressure of terminals 13 and 14maintains disc 15 in contact with the nodes so that a firm contact isformed. Retaining ring 11 retains the entire assembly in a compact,easily assembled capsulation.

What is claimed is:

In a silicon carbide resistor assembly, a one-piece hollow tubeinsulating casing, a first contactor having a circular contact surfaceand a terminal extending radially therefrom, said contact surface havinga convex contour with three convex nodes protruding therefrom, a radialslot in said casing for positioning said terminal radially extendingoutward of said casing, an internal shoulder in said casing forrestraining said first contactor inwardly of said casing, a siliconcarbide disc having a pair of plane contact surfaces, a first of saiddisc surfaces contacting the nodes of said first contactor, a secondcontactor shaped substantially like said first contactor, a secondradial slot in said casing for positioning the terminal of said secondcontactor to extend externally of said casing, said second contactorhaving nodes for contacting said other disc surface, an internal groovein said casing for resting therein a snap ring for restraining saidsecond contactor from axial movement, said ring and casing combinedlypositively holding said contacting surface within said casing.

References Cited in the file of this patent UNITED STATES PATENTS2,021,509 Hastings Nov. 19, 1935 2,143,414 Grisdale Jan. 10, 19392,273,704 Grisdale Feb. 17, 1942 FOREIGN PATENTS 583,564 Great BritainDec. 20, 1946 760,029 Great Britain Oct. 31, 1956

